Chemistry Reference
In-Depth Information
according to the following reaction:
n-hexane
!
9
[Ca
9
OC
2
H
4
OMe
18
]
.
2
HOC
2
H
4
OMe
C H
2
"
2
.
4
Ca C 4HOC
2
H
4
OMe
By contrast, a similar reaction with barium granules followed a different course
51
to yield [H
4
Ba
6
O
OCH
2
CH
2
OMe
14
] which has been characterized by single-crystal
X-ray diffraction studies.
Recently, it has been reported that monomeric Ba[O
CH
2
CH
2
O
n
CH
3
]
2
(
n
D 2or3)
products are obtained in the reactions of barium granules with an oligoether alcohol
52
in tetrahydrofuran (Eq. 2.5):
THF
! Ba[O
CH
2
CH
2
O
n
CH
3
]
2
C H
2
"
Ba C 2HO
CH
2
CH
2
O
n
CH
3
2
.
5
where
n
D 2or3.
The factor(s) determining the variation in the nature of products in the reaction of
Ca/Ba with chelating alcohols obviously require further investigations.
Interestingly, the reaction of barium with a sterically demanding alcohol having
donor functionality yields a volatile derivative
53
with excellent solubility (even in
n
-pentane) (Eq. 2.6):
THF/NH
3
!
H
2
Ba C 2HOCBu
t
CH
2
OPr
i
2
Ba[OCBu
t
CH
2
OPr
i
2
]
2
2
.
6
2.1.2
Group 3 and the f-block Metals
The method involving direct reaction of a metal with alcohol was extended by Mazdi-
yasni
et al
.
54
for the formation of scandium, yttrium, and lanthanide alkoxides using
mercuric chloride (10
3
-10
4
mol per mol of metal) as a catalyst:
HgCl
2
cat
.
!
heat
n
[Ln
OPr
i
3
]
n
C
3
1
Ln C 3Pr
i
OH
(excess)
2
H
2
"
2
.
7
Ln D Sc,Y,Dy,andYb
.
Mercuric chloride appears to form an amalgam with the metal which reacts with
isopropyl alcohol to yield the triisopropoxide. Mazdiyasni
et al
.
54
also noticed that the
use of HgCl
2
in stoichiometric ratio resulted in the formation of alkenoxide contami-
nated with chloride. For example, the reaction of yttrium metal, isopropyl alcohol, and
mercuric chloride in 1:3:4 molar ratio yielded yttrium isopropeneoxide
55
and hydrogen
chloride:
Y C 3HOCH
CH
3
2
C 4HgCl
2
! Y[OC
CH
3
D
CH
2
]
3
C 4Hg C 8HCl C
2
H
2
2
.
8
The above route has also been utilized for the synthesis of neodymium
56
and
yttrium
57
alkoxides as shown by Eqs (2.9) and (2.10):
4Nd C 16Pr
i
OH ! [Nd
OPr
i
3
.
Pr
i
OH]
4
C 6H
2
"
2
.
9
10Y C 30HOC
2
H
4
OMe ! [Y
OC
2
H
4
OMe
3
]
10
C 15H
2
"
2
.
10
